Implantable medical system including multiple sensing modules

Abstract

A medical system includes at least two sensing modules that each generate an optical signal that changes as a function of a physiological parameter of a patient. The sensing modules may be coupled to a common light source and a common receiver via an optically transmissive member. At least a first sensing module that is closest to the light source along a length of the optically transmissive member may include a waveguide to split the light emitted by the light source. A first portion of the light may be directed toward the first sensing module and a second portion of the light may be directed toward a second sensing module that is placed downstream of the first sensing module in a direction substantially along the direction of light flow through the optically transmissive member and away from the light source.

The invention claimed is: 
     
       1. An implantable medical system comprising:
 a light source configured to emit light; 
 an implantable optically transmissive member comprising a waveguide comprising an optical cavity, a first segment and a second segment, the first segment optically coupled to the light source and configured to propagate the light emitted by the light source to a distal end of the first segment, the distal end of the first segment received at a first end of the waveguide so that the light emitted by the light source and propagated from the light source through the first segment toward the distal end of the first segment exits the distal end of the first segment and is received at the optical cavity, the second segment having a proximal end received at a second side of the waveguide, the first side of the waveguide separated from the second side of the waveguide by the optical cavity, wherein the first segment is physically separated from the second segment by the optical cavity and is optically coupled to the second segment through at least one optical path formed through the optical cavity: 
 a light dividing member positioned within the optical cavity and configured to divide the light from the light source received at the optical cavity through the first segment into at least a first portion and a second portion, wherein the light dividing member comprises at least one surface within the optical cavity that occludes a first portion of the optical cavity and is configured to direct the first portion of the light, and wherein a second portion of the optical cavity is unobstructed by the light dividing member, the second portion of the optical cavity comprising the at least one optical path between the first segment and the second segment through the optical cavity for the second portion of light: 
 a first sensing module optically coupled to the first and second segments of the optically transmissive member, the first sensing module configured to receive the first portion of light and generate a first optical signal; and 
 a second sensing module optically coupled to the second segment of the optically transmissive member, the second sensing module configured to receive only the second portion of the light and generate a second optical signal, 
 wherein the first sensing module and the second sensing module are configured to modulate one or more properties of the first and second portions of light as a function of one or more physiological parameters of a patient. 
 
     
     
       2. The implantable medical system of  claim 1 , wherein the light dividing member comprises a first light dividing member, the system further comprising a second light dividing member that divides the second portion of the light into at least a third portion and at least a fourth portion, wherein the second sensing module is configured to receive the third portion of the light. 
     
     
       3. The implantable medical system of  claim 2 , further comprising a third sensing module optically coupled to the optically transmissive member, wherein the optically transmissive member is configured to guide the fourth portion of the light toward the third sensing module. 
     
     
       4. The implantable medical system of  claim 1 , further comprising a receiver configured to receive the first optical signal and the second optical signal and generate electrical signals based on the first and second optical signals, and a processor configured to determine a physiological parameter value of the patient based on at least one of the first or second optical signals. 
     
     
       5. The implantable medical system of  claim 1 , wherein the at least one surface of the light dividing member further comprises a reflective surface configured to direct the first portion of the light from the optical cavity to the first sensing module. 
     
     
       6. The implantable medical system of  claim 1 , wherein the first sensing module comprises a first light filter configured to filter a first wavelength of light from the first portion of the light, wherein the first optical signal comprises the first wavelength of light, and wherein the second sensing module comprises a second light filter configured to filter a second wavelength of light from the second portion of the light, wherein the second optical signal comprises the second wavelength of light. 
     
     
       7. The implantable medical system of  claim 6 , wherein the first and second wavelengths of light are the same. 
     
     
       8. The implantable medical system of  claim 6 , wherein the first and second wavelengths of light are different. 
     
     
       9. The implantable medical system of  claim 6 , wherein at least one of the first or second light filters comprises a diffuse reflective surface. 
     
     
       10. The implantable medical system of  claim 6 , wherein at least one of the first or second light filters comprises an optical material disposed within the first or second sensing modules. 
     
     
       11. The implantable medical system of  claim 1 , further comprising a receiver configured to receive a third optical signal and extract the first and second optical signals from the third optical signal. 
     
     
       12. The implantable medical system of  claim 11 , wherein the first and second optical signals comprise different wavelengths of light, wherein the receiver is configured to extract the first and second optical signals from the third optical signal based on known wavelengths of light of the first and second optical signals. 
     
     
       13. The implantable medical system of  claim 5 , wherein the reflective surface comprises a gold or aluminum surface. 
     
     
       14. The implantable medical system of  claim 1 , wherein the first sensing module, the second sensing module, or both the first and second sensing modules comprises a sensing element that modulates at least one of an amplitude, wavelength, phase, frequency or velocity of the light to generate at least one of the first or second optical signals. 
     
     
       15. The implantable medical system of  claim 14 , wherein the sensing element comprises a deflectable member, a resonating beam, or a combination of the deflectable member and the resonating beam. 
     
     
       16. The implantable medical system of  claim 1 , wherein the first sensing module comprises a first optical resonance sensor configured to modulate a frequency of the first portion of the light, the second sensing module comprises a second optical resonance sensor configured to modulate a frequency of the second portion of the light, or both the first sensing module comprises the first optical resonance sensor and the second sensing module comprises the second optical resonance sensor. 
     
     
       17. The implantable medical system of  claim 1 , wherein the light dividing member is configured to direct the first portion of the light toward tissue of the patient and receive light that is emitted by the light source and reflected by blood of the patient within the tissue, the received light comprising the first optical signal, wherein the first optical signal is indicative of a blood oxygen saturation level of the patient. 
     
     
       18. The implantable medical system of  claim 1 , wherein the first and second sensing modules are distributed along a length of the optically transmissive member. 
     
     
       19. The implantable medical system of  claim 1 , wherein the first sensing module is optically coupled to the first and second segments and the second sensing module is optically coupled to the second segment. 
     
     
       20. The implantable medical system of  claim 1 , wherein the first and second optical signals change as a function of different physiological parameters. 
     
     
       21. The implantable medical system of  claim 1 , wherein the one or more physiological parameters comprise one or more of: a blood pressure, a blood oxygen saturation level, a temperature, a parameter indicative of patient movement, acoustic vibrations, or cardiac activity. 
     
     
       22. A method comprising:
 controlling a light source within a medical device housing to emit light; transmitting the light through an optically transmissive member to first and second sensing modules optically coupled to the optically transmissive member, wherein the implantable optically transmissive member comprises a waveguide comprising an optical cavity, a first segment and a second segment, the first segment optically coupled to the light source and configured to propagate the light emitted by the light source to a distal end of the first segment, the distal end of the first segment received at first end of the waveguide so that the light emitted by the light source and propagated through the first segment toward the distal end of the first segment exits the distal end of the first segment and is received at the optical cavity, the second segment having a proximal end received at a second side of the waveguide, the first side of the waveguide separated from the second side of the waveguide by the optical cavity, wherein the first segment is physically separated from the second segment by the optical cavity and is optically coupled to the second segment through at least one optical path formed through the optical cavity, and 
 wherein the first sensing module is optically coupled to the first and second segments of the optically transmissive member, the second sensing module is optically coupled to the second segment of the optically transmissive member, the light emitted by the light source propagates through the first segment to the first sensing module and through the first and second segments to the second sensing module, the first sensing module comprises a light dividing member positioned within the optical cavity that divides the light received at the optical cavity through the first segment into at least a first portion and a second portion, wherein the light dividing member comprises at least one surface within the optical cavity that occludes a first portion of the optical cavity and is configured to direct the first portion of the light, and wherein a second portion of the optical cavity is unobstructed by the light dividing member, the second portion of the optical cavity comprising the at least one optical path between the first segment and the second segment through the optical cavity for the second portion of light, 
 directing, using the light dividing member and the optical cavity, the light exiting the distal end of the first segment so that the first sensing module receives the first portion of the light, and the optically transmissive member guides the second portion of the light toward the second sensing module, wherein the first and second sensing modules are configured to modulate a property of the first and second portions of light as a function of one or more physiological parameters of a patient; 
 receiving a first optical signal generated by the first sensing module based on the first portion of the light; 
 receiving a second optical signal generated by the second sensing module based on the second portion of the light; and 
 determining a physiological parameter value of a patient based on at least one of the first or second optical signals. 
 
     
     
       23. The method of  claim 22 , further comprising receiving a third optical signal via the optically transmissive member and extracting the first and second optical signals from the third optical signal. 
     
     
       24. The method of  claim 23 , wherein the first and second optical signals comprise different wavelengths of light, wherein extracting the first and second optical signals from the third optical signal comprises extracting the first and second optical signals from the third optical signal based on known wavelengths of light of the first and second optical signals. 
     
     
       25. The method of  claim 22 , wherein the first and second optical signals change as a function of different physiological parameters. 
     
     
       26. The method of  claim 22 , wherein the one or more physiological parameters comprise one or more of a blood pressure, a blood oxygen saturation level, a temperature, or a parameter indicative of patient movement, acoustic vibrations, or cardiac activity.